This invention concerns snowshoes with provision for pitch rotation of the snowshoe deck relative to the boot binding, and especially such pitch-rotating snowshoes wherein some form of spring urges the snowshoe deck to rotate toward a defined neutral position relative to the boot and binding.
Atlas Snowshoe Co. U.S. Pat. No. 5,699,630 shows an example of the type of snowshoe to which this invention applies. The tubing frame-type snowshoe has a boot binding that connects to the frame via a tensioned strap. The strap or straps extend from the binding platform left and right to connections with the tubing frame, wrapping around the frame. This allows rotation of the binding in the pitch direction relative to the snowshoe deck, while also exerting a force as the binding is rotated, urging the binding to rotate back toward a neutral position defined by the strap alignment. The spring function in the snowshoe of U.S. Pat. No. 5,699,630 is primarily accomplished by a slight drawing in of the tubular frame members during pitch pivoting, by which the frame exerts a tensioning return force on the straps and thus a rotational force on the binding platform.
In the patented snowshoe the straps are actually attached to the footbed binding platform in such a way as to establish a neutral position in which the boot binding is tipped forward relative to the snowshoe, that is, a neutral position in which the tail of the snowshoe angles downwardly relative to the boot binding. Thus, as the user walks the snowshoe deck is biased or pre-loaded toward a tail-down, nose-up position, which prevents the snowshoes from catching on snow at the nose end as each snowshoe is advanced. Also, the described suspension system causes the snowshoe frame to follow the foot, tending to hold the snowshoe at the neutral position when the foot is lifted, making maneuvering, such as backing, and jumping easier, as compared to a snowshoe freely-pivoting in pitch. In this spring-loaded suspension system as in the above patent and others of Atlas Snowshoe Company, the suspension arrangement using the strap or straps allows the user to pitch-rotate the binding, from the neutral position, either in a downward direction toward the snowshoe platform or in an upward, deeper-pitch direction toward a larger tilt angle at the rear foot during walking. In either event the spring-bias or pre-load established by the strap suspension will urge the snowshoe deck back toward the neutral position relative to the binding. In most cases the neutral position is at approximately 30° to 45° but it could be from about 10° to about 45°, or it could even be 0° at the lower end of the range, as in some snowshoes having a binding suspended by a “toe chord”. The strap system is also effective at allowing the user's boot to roll relative to the snowshoe deck (articulation). This allows a user to maintain a flat foot position while the deck conforms to terrain on traverses.
Typically the user during walking will position the rear foot in such a way as to tilt the binding forwardly/upwardly beyond the neutral position during part of the gait. This brief deep-pitch angling of the binding beyond the neutral position stores energy in the suspension system whereby the snowshoe deck wants to return up to the neutral position. Soft snow resting on the snowshoe deck is then flipped up onto the user's legs when the deck is allowed to return toward neutral as the toe of the user lifts off the snow. This is commonly known as snow-flip. The phenomenon occurs commonly in 0° neutral position snowshoes.
Although the spring-loaded suspension system of the above patent works very well, some users find the snow-flip effect objectionable. In particular, some users with a particular style of gait tend to generate a considerable snow-flip.
Previous solutions to the problem of snow-flip have been to adjust the bias angle, or to adjust the spring tension to a lighter tension. The adjustment of the bias angle, to the point that the neutral position was at a very high pitch angle, was not practical. The very high bias angle put greater loading on the spring tension when the binding was flat on the snowshoe, and it would allow the snowshoe to hang essentially vertically from the binding. Spring tension adjustment was only partially effective and was not capable of completely eliminating the snow-flip effect.